1. Field of the Invention
The present invention generally relates to keyboards for computers and other devices that need data entry in harsh environments, both indoor and outdoor, and in public access areas.
2. Description of the Prior Art
Prior art keyboards have a moat either around the keys or surrounding the keys. As with a moat when fluid is introduced it is held by the depth of the moat and then must evaporate. If the fluid is water then the residue left after the evaporation process is minimal, but if it is coffee or other fluid that contains sugar or solids, after the evaporation process the solids remain in some gummy or sticky dirt attracting form. One such moat is disclosed in U.S. Pat. No. 6,215,420, a second in FIG. 1 of U.S. Pat. No. 6,056,457 whereas the key caps are shown recessed in the top of the keyboard.
Some prior art keyboards try to minimize the size of the moat by putting a barrier between the keys and various distances up to being coplanar with the top of the key cap. In doing so an operator of the keyboard is hindered by the barrier because if they slightly miss the key when trying to depress the key they hit the barrier thus giving an unnatural typing experience.
Some prior art add a thin flexible elastomer sealing membrane in the moat between the key cap and some part of the keyboard, but these membranes can easily be cut by vandals, by harsh use, or crack when aged, an example is disclosed in U.S. Pat. No. 5,642,950.
Another sealed keyboard as disclosed in U.S. Pat. No. 6,215,420 fabricates the top surface of the keyboard from an elastomer that can be cut by vandals to remove the key caps. When a sealing membrane or elastomer is cut or fails from age there is no inherent design means to stop fluids from getting to the interior of the keyboard.
Some prior art keyboards being used in public access areas have removable key caps that can be removed by vandals from the exterior of the keyboard. These keyboards are meant to be used in office type environments whereas the ease of manufacturing by which the key caps are assembled last out weighs the removability of the key cap by a vandal.
Other sealed keyboards have membrane switches. Membrane being one that by touching a key area the top surface of the keyboard deflects to connect a conductive member to conductive tracks on a printed circuit board. The main drawbacks of these devices are the pressure to make the contact is high, the stroke is short and the life expectancy is low. All sealed prior art uses some type of switches with contacts that have a finite contact actuation life.
Some prior art as disclosed in U.S. Pat. No. 4,417,824 use an interrupter in optical beams to detect a key actuation, and further discloses in FIG. 2 that in the depressed key position the force of furthest depression is stopped by parts of the key mechanism.
It is therefor the primary objective of this invention to dispose a plurality of islands on a top surface of the keyboard and place a key position in each island. As with an island when fluid is introduced it is only held in depth by surface tension and the viscosity of the fluid. The top surface of this keyboard is a planar or descending surface from the base of the island to at least one, or part thereof, side of the keyboard periphery. These islands and a key cap with the section of an umbrella, even without seals, or if a physical seal fails, give the invention an inherent resistiveness from external fluids to interior keyboard fluid contamination.
Briefly, this invention contemplates having a top surface, key caps, key interrupters, and cursor positioning device with a means allowing fabrication from stainless steel or less expensive materials. The key interrupters block optical beams for key detection thus eliminating contacts and contact actuation life. The cursor positioning device being a downwardly floating circular interrupter disposed between and concentric with the center of an inner and outer circular ring of optical emitters and detectors, whereas depending on the amount of downward movement and the position of downward movement by the circular interrupter emission is blocked, or partially blocked, between a particular pair of emitters and detectors that point the direction of cursor movement.
It is a further object of this invention to have stainless steel key caps that are only removable by releasing the key stem from within the keyboard.
It is a further object of this invention to have a seal protected by the key cap whereas only the thick non-flexing portion of the seal is exposed to a user.
It is also a further object of this invention to have optical switches whereas in the most depressed position require no physical contact with any of the switch surfaces.
It is also a further object of this invention that when a key is in the most depressed position the key cap is against the keyboard top surface protecting all internal parts from pressure, or force from harsh use or a vandals blow.
It is also a further object of this invention to allow the keyboard to be easily cleaned.
It is also a further object of this invention is to have a cursor control device that conforms to all aforementioned keyboard objectives. In operation the operator places their fingers on the device and rocks the articulator in the direction they want the cursor to move to position the cursor. And by taping signatures do single and double taps to input single and doubles clicks to the host computer.
It is also a further object of this invention to alternatively have a top surface, key caps, key interrupters, and cursor control device fabricated from plastic.
And it is also a further object of this invention to alternatively have a planar top surface with fasteners stepped in from the periphery to facilitate attaching the keyboard to a mounting surface.